Field
The present invention relates to an optical semiconductor device and, more particularly, to an optical semiconductor device incorporating a semiconductor laser and suitable for use at a radiofrequency.
Background
JP 59-193080 A discloses an optical semiconductor device that receives emergent light from a rear end surface of a semiconductor laser by a photodiode.
In the optical semiconductor device, the semiconductor laser is mounted on a front surface of a mount substrate. For example, in a case where a wiring pattern for connection between the semiconductor laser and lead pins is provided on the mount substrate, there is a need to increase the surface area of the mount substrate. Since the emergent light has an angular divergence, the emergent light can easily strike the mount substrate if the mount substrate is increased in size.